Such components are more simply referred to as contactless components and may, for example, be components known as NFC components. These components are compatible with NFC (Near Field Communication) technology. The NFC component may, for example, be an NFC microcontroller.
The acronym NFC (Near Field Communication) denotes a short-distance, high-frequency, wireless communications technology, which enables exchanges of data between two contactless devices over a short distance, for example, 10 cm.
NFC technology is standardized in documents ISO/IEC 18 092 and ISO/IEC 21 481, but incorporates a variety of pre-existing standards including the type A and type B protocols of the standard ISO/IEC 14 443.
An NFC microcontroller can generally be used either in reader mode or in card mode to establish a dialog with another contactless device, for example, using a contactless communications protocol such as the type A protocol of the standard ISO/IEC 14 443.
In reader mode, the NFC component functions as a reader with respect to the external contactless device which can then be a card or a tag. In reader mode, the NFC component can then read the contents of the external device and write information into the external device.
In card mode, the NFC component then functions as a card or a tag and establishes a dialog with the external device which is this time a reader.
An NFC microcontroller may, for example, be incorporated into a cellular mobile telephone, and the latter can then be used, aside from its conventional telephone function, for exchanging information with the external contactless device.
Numerous applications are thus possible, such as the passage through a toll gate in transportation applications (the mobile telephone acts as a travel ticket) or else payment applications (the mobile telephone acts as a credit card).
The contactless components, such as NFC components, are generally connected to the antenna via an impedance matching circuit to optimize the radio frequency communications. Furthermore, these external components used in this impedance matching circuit, for example, coils and capacitors, need to be precisely dimensioned in such a manner as to allow a correct frequency tuning of the antenna, for example, onto a carrier frequency. For example, the carrier frequency may be 13.56 MHz. This ensures an increased or maximum level of performance.
Generally speaking, differences exist between the theoretical values of these external components and of the antenna and the real values of the latter when they are effectively implemented and physically connected to the NFC component. This is notably due to the technology dispersions in the external components and in the antenna used which can be more significant the lower the quality, notably, of the external components.
This then results in a frequency detuning of the antenna. This frequency detuning of the antenna may also be caused by the magnetic coupling with the antenna of another NFC object.